Dose-response relations and the moderators between different types of exercise with cognitive functions in older people with mild cognitive impairment: A secondary analysis of a randomized clinical trial

Background Identifying the dose-response relations between exercise and cognition is crucial for developing individualized exercise programs. Objective To explore the dose-response relations between different types of exercise and cognition, as well as the potential moderators in older adults with mild cognitive impairment (MCI). Methods This study is a secondary analysis of a randomized clinical trial. Older adults with MCI were randomized to the aerobic exercise (AE) group, resistance exercise (RE) group, or control group, with 36 in each group. Remotely supervised six-month AE training and RE training were conducted separately. Cognitive functions were evaluated at pre- and post-intervention. Results Twenty-eight participants in the AE group and 30 in the RE group were included in dose-response analyses. Paired t-tests demonstrated positive cognitive changes following both AE and RE programs. Linear regressions revealed a significant dose-response relationship between RE and processing speed (estimate = 5.32, 95%CI (2.07,8.56), p = 0.003). Age, body mass index (BMI), and physical activity levels at baseline were significant moderators of the relationship between AE dose and cognitive responses. In contrast, age, sex, and BMI appeared to moderate the RE dose-response relationship, although these findings were less robust. Conclusions Positive dose-response relations may exist among older adults with MCI, particularly between RE dose and processing speed. Some key factors, including age, sex, BMI, and the baseline physical activity level, may influence how individuals respond to exercise dose. Our findings provide preliminary insights for developing personalized exercise programs to optimize intervention efficiency and maximize cognitive benefits. Trial registration number ChiCTR2100045582.